The Siemens 3RT1627-1AG61 is a SIRIUS capacitor contactor built for AC-6 duty — the utilization category that covers switching of capacitor banks for power factor correction. Rated at 35 A and 25 kVAr at 400 V, it handles the high inrush currents and repetitive switching that capacitor loads demand.
This part is flagged as a phased-out product. The manufacturer's stated successor is the SIRIUS 3RT2 series — the current-generation capacitor contactor that replaces this unit. No last-time-buy date is recorded in the available documentation.
The AC-6 rating is the key selection parameter here. Standard power contactors (AC-3 or AC-1) can weld their contacts on capacitor inrush — the 3RT1627-1AG61 is specifically designed with higher making capacity to survive that surge. The 25 kVAr at 400 V figure tells you the maximum capacitor bank size it can switch at that line voltage; size up if your bank exceeds that reactive power. The coil is 100 V AC, not a common 110 V or 230 V control voltage — verify your control transformer matches before wiring.
Side-by-side mounting is permitted with no required spacing, which saves rail space in dense panels.
Environmental range and wiring
Both main and auxiliary circuits use screw-type terminals — no spring-cage here, so factor in screwdriver torque time if you're used to push-in terminations on newer gear. The 1 NO auxiliary contact is built in; if you need more, an auxiliary switch block can be added on top without losing the IP20 front rating.